Which method is used to count white blood cells and red blood cells in a 12-hour urine sample?

The hemacytometer is a specialized counting chamber used for enumerating cells, particularly white blood cells and red blood cells, in various body fluids, including urine. This method allows for accurate counting because the hemacytometer is designed with a ruled grid that helps the technician count cells in a defined volume, making it easier to calculate the concentration of cells per unit volume in the sample.

When analyzing urine, particularly a 12-hour sample, it is essential to obtain precise counts of these cells for diagnostic purposes. The hemacytometer is specifically beneficial in this context because it provides a reliable and quantifiable assessment of the cellular components, aiding in the detection of potential issues such as infection or inflammation.

In contrast, microscopic examination focuses more on visual identification and assessment of the urinary sediment rather than quantifying specific cell counts. Colorimetric analysis measures concentration based on color changes in specific reagents and is not used for counting cells. Centrifugation is a method used to separate components of the urine sample but does not provide a direct count of cells. Thus, the hemacytometer stands out as the most appropriate choice for counting white blood cells and red blood cells in this scenario.